The primary aim of this study is to test the effects of excitation of ventral striatal circuitry via DBS (e.g. DBS-on versus DBS-off) on reward motivation. The investigators predict that stimulation will increase subject willingness to expend effort for rewards and facilitate motivation for reward learning. The investigators further predict that individual differences in the effects of DBS on reward motivation as will be associated with effects of DBS treatment on anhedonic symptoms.

The EEfRT is a multi-trial computer-based task that assess an individual's willingness to expend effort for the chance to earn monetary rewards. We will assess whether stimulation of the Ventral Capsule/Ventral Striatum has an effect on behavior by executing this task with the DBS system on and off.

This task is an additional reward task that assesses reward learning. We will assess whether stimulation of the Ventral Capsule/Ventral Striatum has an effect on behavior by executing this task with the DBS system on and off.

Deep brain stimulator implantation performed at least three months prior to study

Exclusion Criteria:

Subjects unable to visualize stimulus objects with correction

Dementia or other known cognitive deficit

Contacts and Locations

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Please refer to this study by its ClinicalTrials.gov identifier: NCT01590862